US researchers with new findings: Coronavirus Sars-CoV-2 penetrates the body through the nose

  • fromPamela Dörhöfer

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Infection with the Sars-CoV-2 coronavirus does not occur via the throat as assumed. The nose is the entry point for the infection.

  • SARS-CoV-2* often penetrates the body through the nasal mucosa
  • Previously, researchers suspected the throat as an entry route
  • It gets over the nose Corona virus in the lungs, but also in the brain – you can also get all the news in our news app

Not only cold viruses love the mucous membranes of the nose. That too Sars Coronavirus-2 uses them preferentially to penetrate and spread out in the human body. This is what US researchers from North Carolina found out. They published their findings in the “Cell” magazine.

Corona research: The virus takes a different route than expected

In the beginning, many scientists assumed that it was Corona virus it first affects the throat tissue and then migrates into the lower respiratory tract as the infection progresses. This assumption seemed to fit in with the fact that runny nose was initially a rather rare symptom in Covid-19 * and that sore throats generally appear as the first symptoms after infection.

However, the researchers led by Yixuan Hou have now come to the conclusion that the virus takes a different route: In their view, it first attacks cells in the nasal cavity and from there it reaches body parts and deep areas of the lungs. The nose could also be the station through which Sars-CoV-2 migrates into the brain *, which the pathogen can also reach and damage according to current knowledge.

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Coronavirus enters the lungs through the nose

To the infection routes of the virus To investigate, the researchers constructed in the laboratory based on the existing genetic data of SARS-CoV-2 an artificial lookalike that glows green under fluorescent light. Using a highly sensitive method, they also examined the various cell types in the nasal, pharynx and bronchial mucosa to determine the amount of ACE2 receptor they are equipped with. This receptor is at Covid-19 crucial because that virus binds to it to penetrate inside the cells. The scientists found that the density of the ACE2 receptor decreased along the route from the upper to the lower airways. This means that more of these docking sites were present in the cells of the nasal mucosa than in the cells of the throat and bronchi.

In line with this finding, the researchers found that the virus was better able to infect the upper respiratory tract. Another result of these experiments: In all respiratory tracts, the cilia cells in particular were affected by the infection. Cilia are extensions of the cells that perform important tasks in the movement and reception of signals from their surroundings. In the lower airways, for example, their movements allow mucus to be removed.

Sars-CoV-2: partial immunity from other corona viruses

In a second part of the study, the scientists tested using the artificially created Sars Coronavirus-2 the cross-reactivity with antibodies to the related coronaviruses Sars-1 and Mers. * It was shown that antibodies, such as those found in the blood of patients after Sars infection, also increased to a small extent in laboratory tests SARS-CoV-2 could inhibit. This could indicate that people who have survived Sars or Mers are infected with it SARS-CoV-2 have a partial immunity that makes them less ill. Scientists also believe it is possible that such partial immunity also exists in people who have been infected with one of the common corona cold viruses.

The infectiologist Bernd Salzberger from the Regensburg University Hospital, President of the German Society for Infectious Diseases, who was not involved in the study, describes the methods of the US researchers as “new and elegant”. Together with the data from the histological samples (tissue samples), “an image of the infection” is thus designed: “At the beginning the nasal mucosa becomes infected, then the lung is most likely to become infected by aspiration of mucus.” However, the results could not the conclusion that the other way – direct lung infection – does not occur. However, it now appears to be “less plausible”.

Sars-CoV-2 infected via the respiratory tract: nose as access for coronavirus

However, a direct application to prevent infection with Covid-19 cannot be derived from the study: “The path of the virus is definitely via the respiratory tract.” Specific prevention is therefore “difficult to imagine”. However, if one assumes that the nose becomes infected first and the pulmonary mucosa does not follow until later, there would be time slots to prevent the development of a lung infection with therapy.

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By Pamela Dörhöfer

There is a lot of uncertainty surrounding the new type of corona virus. We answer questions about Corona and the lung disease Covid-19. *

* is part of the nationwide Ippen Digital Network.

Rubric list picture: © imago / UIG

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